There is still considerable uncertainty about the accurate classification of human hematopoietic tumors, as well as considerable variability in prognosis and in response to treatment, not only among different hematopoietic tumors, but also within any one diagnostic category. More precise diagnosis and definition of the relationships between these tumors is therefore important, not only in terms of reaching a clearer understanding of their cellular origins, but also in predicting prognosis, evaluating current treatment regimens, and developing more effective methods of therapy. The main purpose of this Program Project is to carry out a comprehensive clinical laboratory investigation of all varieties of hematopoietic tumors, with emphasis on correlating the results of newer laboratory studies which have potential clinical relevance with conventional hematological and pathological diagnostic criteria, and with clinical data on staging, responsiveness to treatment and survival. The investigations include determination of surface and biochemical markers, receptors, cytokinetic parameters, size distribution, clonogenic potential in short-term culture systems, response to mitogens, interactions with other cell types in culture, establishment of human tumor cell lines, ultrastructural cytology, cytogenetics, and DNA and RNA histograms. Th eventual goal is to help develop an objective and scientific classification system for human hematopoietic tumors based on the origins and functional properties of the cells. Once an accurate classification system has been formulated which will permit us to reliably identify the critical prognostic factors at the time of diagnosis, it should be possible to plan more rational and appropriate treatment programs for the hematopoietic tumors.